The present invention relates generally to the field of machines for locking sheets of material together by deforming the edges of the sheets and by deforming a metal cap to form a common seam. More specifically, this invention relates to a machine for progressively forming a seam at the adjoining edges of metal roof sheets of the type having such edges configured to define a so-called "standing rib joint." A sealing cap encloses the edges of the roof sheets which define the standing rib. The seaming machine serves a two-fold function, viz.,
(1) deforming of the sealing cap to form a seal; and PA0 (2) bending of the edge portions of the roof panels to connect the latter together simultaneously with the bending of the sealing cap.